Method and apparatus for shipping and storing combustible gases



Sept. l, 1953 E. H. BROWN METHOD AND APPARATUS FOR SHIPPING AND STORING COMBUSTIBLE GASES Filed-Feb. ze, 1952 Patented Sept. I1, 1953 METHOD AND APPARATUS FOR SHIPPING AND STORING COMBUSTIBLE GASES Edwin H. Brown, Elm Grove, Wis., assignor to Union Stock Yards & Transit Company, Chicago, Ill., a corporation of Illinois Application February 26, 1952, Serial No. 273,527

13 Claims.

My invention relates to method of and apparatus for shipping and storing combustible gas, and has for one object to make it possible to ship and store large amounts of combustible, highly volatile gas in liquid condition without any danger of explosive mixture of gas and air.

Hydrocarbon gases are liquid at very low temperatures and the liquefied gas can be stored at substantially atmospheric pressure, only if the gas evaporating from the liquid, as a result of heat entering the liquid mass can be safely clisposed of.

It is of the utmost importance when dealing with large volumes or weights of a combustible gas such as methane and the like to insure that both in and around the tank or receiver in which the liquefied gas is stored, there is no possibility of the formation of an explosive cr combustible air gas mixture. Since with storage at atmospheric pressure there will always be a substantial amount of gas evaporating from the liquid, steps must be taken under all circumstances to insure that air does not have the opportunity to enter the area in which the gas either in liquid or gaseous form is found.

The most effective Way of bringing this about is to insure that leakage of evaporated gas, if any should take place, Will result in the evaporated gas being discharged only into an inert atmosphere which will not support combustion. Carbon dioxide gas which is entirely non-combustible yand entirely inert so far as any dangerous mixing with methane is concerned is an exceedingly satisfactory medium for preventing air methane contact.

I propose to charge the receiver, in which methane is to be stored, with carbon dioxide, the carbon dioxide being heavier than air will fill the receiver and purge it of air and will remain in the receiver preventing air entrance as the liquelied cold methane is introduced. The liquefied methane will be at such a low temperature that the carbon dioxide will freeze, forming Dry Ice which remains below or mixed with the liquefied methane. Thus charging the receiver with the liquefied methane will result in little if any loss of carbon dioxide.

As the liquid evaporates, filling the space above the liquid with gaseous methane, no air will be able to penetrate the tank. The pressure set up by the evaporation of the methane will be sufiicient to insure an outward fiow thereof to a point at which it is stored or used and since there will be pressure slightly above atmospheric in the receiver, no air can enter.

When the receiver is emptied of meth-ane, the temperature will rise, the carbon dioxide will evaporate and again fill the receiver, thus preventing entrance of air. Since there was no appreciable loss of carbon dioxide when the tank was lled with methane, there will still be enough l stances, methane storage and shipment at atmospheric pressure becomes safe. The only time methane comes in contact with the air will be when it is discharged from the receiver and mixed with air under controlled conditions for burning.

Carbon dioxide both in gaseous form, in bottles and in solid form as Dry Ice is an article of commerce and easily available and may therefore be used in either form in connection with my invention.

If gaseous carbon dioxide is to be used, it will be caused to iiow into the empty tank which is ultimately to contain methane. Since the carbon dioxide heavier than air, it will sink to the bottom of the tankand as the tank or receiver is filled with carbon dioxide, the air will be purged from the receiver. The receiver will then be completely filled with carbon dioxide with no air in it. Assuming that the receiver is in a vessel as illustrated, the vessel will also be purged of air by liowing carbon dioxide into the space between the receiver and the vessel walls and any piping leading to or from the receiver Will also be filled with carbon dioxide by the application of sufficient pressure to insure that all the air is expelled and the carbon dioxide has flowed into and filled all the piping.

If desired, instead of flowing carbon dioxide into the receiver and vessel or housing enclosing 4.0 it, Dry Ice may be deposited in the receiver and in the space between the receiver and the vessel through any suitable hatchway which will then be closed and since the vessel and tank will at that time be at temperature far above the temperature required in freezing Dry Ice, the Dry Ice will evaporate, filling the tank and the vessel and expelling all the air therefrom.

The insulating material encircling the receiver or tank owes much of its insulation to the air space surrounding the insulating particles so these spaces must also be purged of air to insure that in the event of any leakage from the inner trank toward the outside along anything except the usual discharge channels, there Will be no mixture of methane and air. So carbon dioxide or other inert gases must also be provided within the insulating space to insure the exclusion of air. While carbon dioxide is inexpensive and easily obtained, it solidifies at temperatures substantially the temperature of the liquid methane so under some circumstances, it will be desirable to substitute for carbon dioxide in the insulating space only gas which will not support combustion, nitrogen for example being such a gas.

When this purging of the air has been completed, it is safe to charge theM receiver with liquefied methane. rFhis will be done by pumping or flowing liquefied methane into the receiver. Methane being at temperatures in the order of 258 degrees F. will, as the receiver fills, progressively cool and congeal the carbon dioxide so that when the receiver has been filled to its normal maximum level, the carbon dioxide will have frozen and be reduced in volume to compensate ior the introduction of the liquid methane. The tank or receiver will then be filled with liquid methane plus solidiiied carbon dioxide. If the carbon dioxide settles to the bottom of the tank, well good. Since the process is a gradual one, there may be some iiitermixture of solid carbon dioxide and liquid methane.

The methane which evaporates oli the surface of the liquid at approximately atmospheric pressure will displace the carbon dioxide in the piping. The insulation of the receiver will prevent such chilling of the carbon dioxide surrounding the tank as would cause the carbon dioxide to lose its gaseous form. I thus have a tank inl a vessel, the tank containing methane in liquid forni, methane in gaseous form and oxide in solid form, and the tank is surroiuided by an atmosphere of carbon dioxide in gaseous form.

The vaporized hydrocarbon evaporated from the surface of the liquid gas will be at the ternperature of the liquid and will now out through the insulating chamber between the outer and inner walls of the receiver to furnish a cold blanket about the liquid hydrocarbon. This blanket may be formed by a pipe or pipes in the space between the two Walls associated with the insulating material or under some circumstances, if both walls are completely gas tight, the cold gas may be admitted freely into the space between the two walls and drawn off for discharge at some point removed from the point where the gas enn ters the insulating space.

Thus any heat entering the receiver must first pass through this blanket of cold gas before it reaches the liquid, thus reducing the rate at which liquid evaporates to a point such that excessive loss in shipment will not ensue.

My invention is illustrated more or less diagrammatically in the accompanying drawing. Like parts are indicated by like characters throughout the specication and drawings.

rlhe gas receiver l adapted to contain liquefied hydrocarbon comprises an inner wall 2, an outer wall 3, the Walls being spaced apart in general parallelism by any suitable non-conducting structure 4. Insulation material 5, such as powdered cork, celocel or the like is located between the two walls 3 and 4. is a hatch which may be opened for the deposit of Dry Ice or solidified carbon dioxide in the receiver l.

l is a removable supply pipe associated with the hatch cover 8 through which, if desired, gaseous carbon dioxide may be introduced. Since carbon dioxide or any other such inert gas usable for this purpose is heavier than air, the pipe 'i discharges adjacent the bottom of the tank so that the purging gas will be discharged tothe bottom of the tank, will lill the tank, the air being gradually expelled therefrom. With the hatch in open position air may escape as it is displaced by the heavier carbon dioxide. When liquefied man 4 cold hydrocarbon is introduced through pipe l to ll the receiver, the carbon dioxide conceals and remains in the receiver as Dry Ice.

9 is a port in the inner wall of the receiver. It communicates with a Pipe or pipes lil extending throughout the space between the walls 2 and 3. The pipe Il) communicates at the other end with a second port Il in the outer wall in register and with a pipe I2 through which methane is discharged from the tank. If desired, the pipe lll may be omitted. In that case, evaporated methane leaves the receiver through the port S, passes through the space between the walls i2 and 3 and is discharged through the pipe i2 from the outer portion of the receiver, the structure d in that case being so disposed as to guide the gas on its way from the port S to the port l so as to to surround the entire area of the inner tank.

20 is a barge having a deck I3, the receiver l being supported in the barge by any suitable means shown diagrammatically as the cradle lll. l5 is a port in the deck of the barge adapted to be closed by a hatch cover It with a pipe l'l through which gaseous carbon dioxide may be admitted or Dry Ice may be introduced directly through the hatch as the case may be. In either case, air will be allowed to escape through the hatch as it is displaced by carbon dioxide, until the receiver is completely surrounded by an atmosphere of carbon dioxide lling that part of the barge in which the receiver is located.

While the combustible hydrocarbon with which I am primarily concerned is methane, a highly volatile gas liquefying at approximately 258 degrees F. it is obvious that other combustible gases might equally Well be treated and stored as I propose, the point being that the hydrocarbon or combustible material is of the gaseous type which evaporates at temperatures immediately below a temperature far below the normal ambient atmospheric temperature. It is also to be emphasized that the storage that I propose always takes place at or just about at atmospheric pressure, thus avoiding the necessity of tanks heavy enough and strong enough to support anything except very slightly above atmospheric pressures. I have not illustrated the means for supplying the liqueed methane to the tank. It can be supplied through a pipe similar to pipe l or even through pipe 'I but under these circumstances the pipe would be withdrawn so as to discharge the liquid at a point nearer the top than the bottom of the tank.

The coil l0 is spaced from both the outer and inner walls of the tank so that the evaporated gas that is discharged through the coil le will not be exposed to the same temperature as the tank. Thus it is warmed by the entrance of heat through the insulation and will be at a higher temperature than the tank or receiver. At the same time it is out of contact with the outer wall because it is undesirable to have the outer Wall at the temperature of the gas as it is discharged because this might result in condensation at the outer WallV of the tank.

20 is a sleeve extending inwardly through the outer wall 3 at the bottom through which carbon dioxide or other gaseous material may be forced into the intestices of the insulation, thus causing air to be purged through the pipe 2| controlled by valve 2,2. Under some circumstances, after such purging of air methane itself at or about atmospheric pressure may be allowed to penetrate the space between the walls '2 and 3 through any suitable pipe 23 communicating with the upper portion of the inner tank 2 and discharging into the lower portion of the insulating space, any leakage through the wall 3 being not dangerous because the methane would merely mix With the carbon dioxide in the hull of the barge.

Iclaim:

1. The method of storing cold, liquefied combustible gas which consists in providing a gas tight zone, introducing carbon dioxide into the zone to expel the air, then supplying liquefied combustible gas to the zone at `temperature such that the carbon dioxide is frozen and reduced in volume, until the zone is substantially filled with liquefied hydrocarbon, the solidified carbon dioxide and some of the hydrocarbon in gaseous condition.

2. The method of storing cold, liquefied combustible gas which consists in providing a gas tight zone, introducing carbon dioxide into the zone to expel the air, then supplying liquefied combustible gas to the zone at temperature such that the carbon dioxide is frozen and reduced in volume, until the zone is substantially filled with liquefied hydrocarbon, the solidified carbon dioxide and some of the hydrocarbon in gaseous condition, al1 at substantially atmospheric pressure.

3. The method of storing cold, liquedfied combustible hydrocarbon gases which consists in providing a gas tight storage zone, purging it of air, by filling it completely With carbon dioxide whereby the air is expelled, then supplying liqueed hydrocarbon to the zone until the carbon dioxide is solidified and the zone is completely filled With it and liqueed gaseous hydrocarbon, maintaining the solidified carbon dioxide in the zone at all times in quantities suiiicient after the liquefied hydrocarbon has evaporated and been Withdrawn and the temperature of the zone raised to refill the zone with gaseous carbon dioxide in such quantity as to prevent the entrance of air into the zone.

4. The method of storing cold, liquefied combustible hydrocarbon gases which consists in providing a gas tight storage zone, purging it of air, by filling it completely with carbon dioxide whereby the air is expelled, then supplying liquefied hydrocarbon to the zone until the carbon dioxide is solidified and the zone is completely filled with it and liquefied gaseous hydrocarbon all at substantially atmospheric pressure, maintaining the solidified carbon dioxide in the zone at all times in quantities sufficient after the liquefied hydrocarbon has evaporated and been withdrawn and the temperature of the zone raised to refill the zone With gaseous carbon dioxide in such quantity as to prevent the entrance of air into the zone.

5. The method of storing cold, liquefied combustible hydrocarbon gas which consists in providing a gas tight storage zone, introducing carbon dioxide thereinto until all air has been expelled, introducing liquefied hydrocarbon into the zone at temperatures sufficient to congeal the carbon dioxide, continuing the introduction of the liquefied hydrocarbon to fill the zone with liquefied and gaseous hydrocarbon and maintaining a carbon dioxide atmosphere outside of and cornpletely surrounding the zone.

`6. The method of storing cold, liqueed combustible hydrocarbon gas which consists in providing a gas tight storage zone, introducing carbon dioxide thereinto until all air has been expelled, introducing liquefied hydrocarbon into the zone at temperatures sufficient to congeal the Carbon dioxide, continuing the introduction of the liquefied hydrocarbon to iill the zone with liquefied and gaseous hydrocarbon all at substantially atmospheric pressure and maintaining a carbon dioxide atmosphere outside of and completely surrounding the zone.

7. The method of storing cold liquefied combustible hydrocarbon which consists in providing a gas tight storage zone, filling Such zone With carbon dioxide in gaseous form adequate to expel all the air therefrom, maintaining outside of the storage zone an atmosphere of carbon dioxide completely surrounding the zone, discharging cold liquefied combustible hydrocarbon into the zone to congeal and displace the carbon dioxide.

8. The method of storing cold liquefied combustible hydrocarbon which consists in providing a gas tight storage zone, filling such zone with carbon dioxide in gaseous form adequate to expel all the air therefrom, maintaining outside of the storage zone an atmosphere of carbon dioxide completely surrounding the zone, discharging cold liquefied combustible hydrocarbon into the zone to congeal and displace the carbon dioxide and fill the zone with frozen carbon dioxide and the combustible hydrocarbon in liquefied and gaSeOuS form.

9. In combination, a receiver, containing solid carbon dioxide, cold, liquefied, high volatile, methane and gaseous methane together filling the receiver and all at substantially atmospheric pressure.

10. In combination, a receiver containing solid carbon dioxide, cold, liquefied, high volatile, methane and gaseous methane together filling the receiver and al1 at substantially atmospheric pressure, the amount of solid carbon dioxide being such as to completely fill the receiver when in gaseous form.

11. In combination, a receiver containing solid carbon dioxide, cold, liquefied, high volatile, methane and gaseous methane together filling the receiver and al1 at substantially atmospheric pressure, a housing enclosing, and containing a body of carbon dioxide completely surrounding the receiver.

12. In combination, a receiver containing solid carbon dioxide, cold, liquefied, high volatile, methane and gaseous methane together filling the receiver and all at substantially atmospheric pressure, the amount of solid carbon dioxide being such as to completely fill the receiver when in gaseous form, a housing enclosing and containing a body of carbon dioxide completely surrounding the receiver.

13. The method of storing cold, liquefied, combustible hydrocarbon which consists in providing a gas tight storage zone, filling such zone with an inert gas adequate to expel all the air therefrom, maintaining outside of the storage zone an atmosphere of inert gas completely surrounding the zone, discharging cold, liquefied combustible hydrocarbon into the zone to displace the inert gas.

EDWIN H. BROWN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,147,729 Hurlbrink s July 27, 1915 2,282,997 Edmundson May 12, 1942 2,317,836 Weaver Apr. 27, 1943 2,507,380 Morrison May 9, 1950 

